Grease Trap vs. Grease Interceptor: What LA Restaurants Need to Know

If you operate a restaurant in Los Angeles, you have probably heard the terms "grease trap" and "grease interceptor" used interchangeably. They are not the same thing. They are different pieces of equipment, sized for different volumes, installed in different locations, and pumped on different schedules. Confusing them can lead to compliance violations, surprise costs, and inspection failures.

This guide explains the difference, when each is required under LAMC Section 171, and how to know which one your restaurant actually needs.

The Quick Definition

A grease trap is a small device, typically under 100 gallons, installed inside the kitchen near the source of FOG (fats, oils, and grease). Think of it as a point-of-use device. It catches grease from a single sink or a small group of fixtures before that grease enters the building's drain line.

A grease interceptor is a much larger device, typically 500 to 2,000+ gallons, installed in-ground outside the building. It catches grease from the entire kitchen's drainage system before that drainage enters the public sewer. Think of it as a building-level device.

The difference is not just size. They have different installation requirements, different inspection rules, different pump-out schedules, and require different vendor equipment to service.

When Does LA Require Each?

LAMC Section 171 and the LA Sanitation FOG Control Program set the requirements. The choice between trap and interceptor depends on a few factors:

Total seating capacity of the food service establishment
Estimated daily wastewater discharge in gallons
Type of food preparation (fryers, woks, char-broilers generate more grease than salad prep)
Existing plumbing and whether the building has space for in-ground equipment

In general, smaller establishments (small cafes, coffee shops, food kiosks, single-fixture prep areas) qualify for grease traps. Larger restaurants with multiple cooking lines, full-service kitchens, and high seating counts are required to install grease interceptors. The exact threshold is set by LA Sanitation and reviewed during plan check by the Los Angeles Department of Building and Safety (LADBS).

If you are opening a new restaurant or doing a tenant improvement, the decision is made during plan check. If you are operating an existing kitchen and unsure what you have, look at where the equipment is. Inside the kitchen near a sink? Probably a trap. Outside in the alley with a manhole cover? Probably an interceptor.

How They Work

A grease trap is a passive device. Wastewater enters the trap, flows slowly through baffles that slow the water down, and the difference in density does the rest. Grease floats to the top, water flows out the bottom. Solids sink. The trap holds the grease and solids until it is pumped.

Interceptors work the same way but at a much larger scale. They use multiple chambers to give the wastewater more time to separate. The first chamber catches solids and the bulk of the grease. The second and sometimes third chambers polish the water before it leaves for the sewer. Because interceptors process the full kitchen output, they handle much higher volumes and need correspondingly larger storage.

Both types are passive. There are no pumps, no filters, no electronics. They work by gravity and density alone. The only maintenance is pumping them out before they fill up, and that is where most compliance failures happen.

Pump-Out Schedules

LA Sanitation requires both grease traps and grease interceptors to be pumped before they reach 25% capacity, or every 90 days at minimum, whichever comes first.

In practice, the schedules look very different:

Grease traps in moderate-volume kitchens often need pumping every 30 to 45 days. The 25% threshold is reached fast because the trap is small. A 50-gallon trap holds only 12.5 gallons of grease before it must be pumped.

Grease interceptors in similar kitchens often go 60 to 90 days between pump-outs. A 1,000-gallon interceptor can hold 250 gallons of grease before reaching 25%. But the volume going into it is also much higher, so the schedule still matters.

High-volume kitchens (Korean BBQ, fryer-heavy concepts, breakfast spots with lots of bacon) generate more grease and need shorter intervals regardless of equipment type. Your vendor should recommend a schedule based on volume measurements from your first few pump-outs.

Vendor Equipment Differences

This is where the trap-versus-interceptor distinction matters most for scheduling. Grease traps and grease interceptors require different vendor equipment.

Grease traps are pumped with smaller vacuum trucks (sometimes called "trap trucks"). These can fit in tight kitchens, work through standard service doors, and handle the relatively small volumes a trap holds. Many vendors who service traps cannot service interceptors at all.

Grease interceptors require larger vacuum trucks with bigger tanks, longer hoses, and the ability to handle 1,000+ gallons of waste in a single visit. They need outdoor access, manhole clearance, and often a wider truck footprint than traps. Vendors who specialize in interceptors typically charge more per service but handle the higher volume.

If you have an interceptor, do not assume any pumping vendor can service it. Confirm that they handle your specific equipment size and have the right truck. GreaseGrid's vendor matching takes equipment type into account during the bid process.

Documentation Requirements

Both equipment types fall under the same documentation rules. After every pump-out you need:

Waste manifest showing volume removed, hauler details, and disposal facility
Service record with date, time, and trap/interceptor identifier
Vendor credentials (current business license, waste hauler permit, liability insurance)
Photos before and after the service when possible

LA Sanitation inspectors can ask for these documents during routine inspections. Restaurants that cannot produce them face corrective action notices, fines, and in serious cases, suspension of food service permits. The inspector does not care whether you have a trap or an interceptor. They care whether you can prove regular service.

Common Mistakes

A few patterns we see repeatedly:

Assuming a trap is enough for a high-volume kitchen. If you opened with a small trap and your business has grown, you may be exceeding what the trap can handle. Frequent backups or strong odors are warning signs. Talk to a plumber about whether you need an interceptor upgrade.

Skipping pump-outs because the trap "looks fine." The 25% capacity rule exists because grease traps fail silently. By the time you can see grease in the sink, the trap is already overflowing into the drain line.

Using unlicensed haulers for cheap pump-outs. LA Sanitation requires licensed waste haulers. Using an unlicensed hauler creates a compliance violation that can outlast the cheap service. The waste manifest from an unlicensed hauler is not valid for inspections.

Mixing trap and interceptor schedules in your records. If you have both (some restaurants do for different parts of the kitchen), maintain separate records. Inspectors check each piece of equipment individually.

How GreaseGrid Handles the Difference

GreaseGrid's intake form asks about your equipment type, capacity, and access details up front. We match you with vendors who service your specific equipment, schedule pump-outs at the right interval based on your volume, and produce documentation formatted for inspector review. Whether you have a small kitchen trap or a 2,000-gallon interceptor, the workflow is the same on your end: submit a request, the right vendor shows up, you get a proof packet.

If you are not sure what equipment you have, contact us and we can help you identify it during intake. Or request service and the vendor will confirm during their site visit.